Allow creation of ATMOS sync on channel 14.

[libdcp.git] / src / sound_asset_writer.cc

diff --git a/src/sound_asset_writer.cc b/src/sound_asset_writer.cc
index 8df4d911a0334377bbe01f7b71e71581cba0f648..ff1d02c23057fd5458aa5826ff1675a0884e8ed7 100644 (file)
--- a/src/sound_asset_writer.cc
+++ b/src/sound_asset_writer.cc
@@ -1,5 +1,5 @@
 /*
-    Copyright (C) 2012-2014 Carl Hetherington <cth@carlh.net>
+    Copyright (C) 2012-2020 Carl Hetherington <cth@carlh.net>
 
     This file is part of libdcp.
 
@@ -31,6 +31,7 @@
     files in the program, then also delete it here.
 */
 
+#include "bitstream.h"
 #include "sound_asset_writer.h"
 #include "sound_asset.h"
 #include "exceptions.h"
@@ -43,6 +44,8 @@
 using std::min;
 using std::max;
 using std::cout;
+using std::string;
+using std::vector;
 using namespace dcp;
 
 struct SoundAssetWriter::ASDCPState
@@ -53,12 +56,17 @@ struct SoundAssetWriter::ASDCPState
        ASDCP::PCM::AudioDescriptor desc;
 };
 
-SoundAssetWriter::SoundAssetWriter (SoundAsset* asset, boost::filesystem::path file)
+SoundAssetWriter::SoundAssetWriter (SoundAsset* asset, boost::filesystem::path file, bool sync)
        : AssetWriter (asset, file)
        , _state (new SoundAssetWriter::ASDCPState)
        , _asset (asset)
        , _frame_buffer_offset (0)
+       , _sync (sync)
+       , _sync_packet (0)
 {
+       DCP_ASSERT (!_sync || _asset->channels() >= 14);
+       DCP_ASSERT (!_sync || _asset->standard() == SMPTE);
+
        /* Derived from ASDCP::Wav::SimpleWaveHeader::FillADesc */
        _state->desc.EditRate = ASDCP::Rational (_asset->edit_rate().numerator, _asset->edit_rate().denominator);
        _state->desc.AudioSamplingRate = ASDCP::Rational (_asset->sampling_rate(), 1);
@@ -87,6 +95,10 @@ SoundAssetWriter::SoundAssetWriter (SoundAsset* asset, boost::filesystem::path f
        memset (_state->frame_buffer.Data(), 0, _state->frame_buffer.Capacity());
 
        _asset->fill_writer_info (&_state->writer_info, _asset->id());
+
+       if (_sync) {
+               _fsk.set_data (create_sync_packets());
+       }
 }
 
 void
@@ -115,14 +127,19 @@ SoundAssetWriter::write (float const * const * data, int frames)
 
                /* Write one sample per channel */
                for (int j = 0; j < ch; ++j) {
-                       /* Convert sample to 24-bit int, clipping if necessary. */
-                       float x = data[j][i];
-                       if (x > clip) {
-                               x = clip;
-                       } else if (x < -clip) {
-                               x = -clip;
+                       int32_t s = 0;
+                       if (j == 13 && _sync) {
+                               s = _fsk.get();
+                       } else {
+                               /* Convert sample to 24-bit int, clipping if necessary. */
+                               float x = data[j][i];
+                               if (x > clip) {
+                                       x = clip;
+                               } else if (x < -clip) {
+                                       x = -clip;
+                               }
+                               s = x * (1 << 23);
                        }
-                       int32_t const s = x * (1 << 23);
                        *out++ = (s & 0xff);
                        *out++ = (s & 0xff00) >> 8;
                        *out++ = (s & 0xff0000) >> 16;
@@ -149,6 +166,11 @@ SoundAssetWriter::write_current_frame ()
        }
 
        ++_frames_written;
+
+       if (_sync) {
+               /* We need a new set of sync packets for this frame */
+               _fsk.set_data (create_sync_packets());
+       }
 }
 
 bool
@@ -168,3 +190,87 @@ SoundAssetWriter::finalize ()
        _asset->_intrinsic_duration = _frames_written;
        return AssetWriter::finalize ();
 }
+
+
+/** Calculate and return the sync packets required for this edit unit (aka "frame") */
+vector<bool>
+SoundAssetWriter::create_sync_packets ()
+{
+       /* Parts of this code assumes 48kHz */
+       DCP_ASSERT (_asset->sampling_rate() == 48000);
+
+       /* Encoding of edit rate */
+       int edit_rate_code = 0;
+       /* How many 0 bits are used to pad the end of the packet */
+       int remaining_bits = 0;
+       /* How many packets in this edit unit (i.e. "frame") */
+       int packets = 0;
+       Fraction const edit_rate = _asset->edit_rate ();
+       if (edit_rate == Fraction(24, 1)) {
+               edit_rate_code = 0;
+               remaining_bits = 25;
+               packets = 4;
+       } else if (edit_rate == Fraction(25, 1)) {
+               edit_rate_code = 1;
+               remaining_bits = 20;
+               packets = 4;
+       } else if (edit_rate == Fraction(30, 1)) {
+               edit_rate_code = 2;
+               remaining_bits = 0;
+               packets = 4;
+       } else if (edit_rate == Fraction(48, 1)) {
+               edit_rate_code = 3;
+               remaining_bits = 25;
+               packets = 2;
+       } else if (edit_rate == Fraction(50, 1)) {
+               edit_rate_code = 4;
+               remaining_bits = 20;
+               packets = 2;
+       } else if (edit_rate == Fraction(60, 1)) {
+               edit_rate_code = 5;
+               remaining_bits = 0;
+               packets = 2;
+       } else if (edit_rate == Fraction(96, 1)) {
+               edit_rate_code = 6;
+               remaining_bits = 25;
+               packets = 1;
+       } else if (edit_rate == Fraction(100, 1)) {
+               edit_rate_code = 7;
+               remaining_bits = 20;
+               packets = 1;
+       } else if (edit_rate == Fraction(120, 1)) {
+               edit_rate_code = 8;
+               remaining_bits = 0;
+               packets = 1;
+       }
+
+       Bitstream bs;
+
+       Kumu::UUID id;
+       DCP_ASSERT (id.DecodeHex(_asset->id().c_str()));
+
+       for (int i = 0; i < packets; ++i) {
+               bs.write_from_byte (0x4d);
+               bs.write_from_byte (0x56);
+               bs.start_crc (0x1021);
+               bs.write_from_byte (edit_rate_code, 4);
+               bs.write_from_byte (0, 2);
+               bs.write_from_byte (_sync_packet, 2);
+               bs.write_from_byte (id.Value()[i * 4 + 0]);
+               bs.write_from_byte (id.Value()[i * 4 + 1]);
+               bs.write_from_byte (id.Value()[i * 4 + 2]);
+               bs.write_from_byte (id.Value()[i * 4 + 3]);
+               bs.write_from_word (_frames_written, 24);
+               bs.write_crc ();
+               bs.write_from_byte (0, 4);
+               bs.write_from_word (0, remaining_bits);
+
+               ++_sync_packet;
+               if (_sync_packet == 4) {
+                       _sync_packet = 0;
+               }
+       }
+
+       return bs.get();
+}
+